The invention relates to flow control and more particularly, to the control of fluid flow with respect to the infusion and aspiration of fluids in venous and arterial systems.
A common container for medical fluids is a plastic pouch which contains saline, i.e. a salt solution used in investigation of biological and physiological processes. The contents of such a container are carried by a conduit, typically plastic tubing, through a "check" valve that is used to prevent backflow.
In addition, other check valves can be used with the conduit to provide for the infusion and/or aspiration of other substances, such as medicaments, body fluids, and anesthetics. Infusion is commonly used to introduce saline or other medical fluids into veins, while aspiration is commonly used to draw fluids from body cavities.
The ordinary check valve used with conduits from medicinal containers functions by the deflection of an elastomeric element towards and away from a valve seat. The deflection is towards the valve seat in order to prevent flow, and away from the seat to permit flow.
In some cases the control of fluid flow is with respect to a multiplicity of channels that have varying degrees of convergence with one another. A typical multichannel arrangement makes use of connectors which permit the intercoupling of flow channels. For example, when two channels are to be joined to permit a common output, the connector can take the form of a fitting that resembles a "Y". When one of the channels terminates in an infusion site, the prior practice has been to access the site by needles, which are undesirable.
Because of the desirability of achieving needleless injection and infusion of fluids, one effort has resulted in Rogers et al. U.S. Pat. No. 5,006,114 of Apr. 9, 1991, in which a valve assembly has a Luer lock on an inlet, and movable piston seals the inlet.
When a syringe is attached to the Rogers inlet the piston is displaced to unseal a fluid channel which connects the end of the syringe to an outlet, and then to a device connected to a patient. When the syringe is removed from the inlet the piston is moved to its original closed position by an internal spring of the valve. This device suffers from the disadvantage that the requirement of a spring for acting against the piston results in a force against the inserted Luer tip that increases as the piston is displaced.
In addition, the Rogers medical valve assembly provides an outlet channel that is displaced at an angle in relation to the inlet. As a consequence of this angular displacement, it is difficult to manufacture the device since there is a tendency for flash to accumulate at the entrance of the outlet channel in the vicinity of the piston. In addition, the angular configuration of the Rogers valve does not lend itself to manifold application.
Moreover, the Rogers design is intended for a Luer fitting which does not have a taper so that when the conventional tapered Luer fitting is employed, it can become jammed in the straight line walls of the inlet.
An attempt to overcome the disadvantages of Rogers is disclosed in Raines, U.S. Pat. No. 5,147,333, which issued Sep. 15, 1992. In the Raines patent there is accommodation for a tapered Luer fitting, but there is the continued disadvantage of the necessity for using a spring to urge a piston or spool forwardly during closure of the valve and rearwardly when the valve is being opened. As a result, the disadvantageous increase in spring force with displacement continues to be present.
Furthermore, the Raines "backcheck" valve requires a pair of vertically offset ports that extend laterally from a tubular body and the spool or piston is disposed between the ports. In addition, like the predecessor Rogers valve, the piston or spool in Raines requires at least one projection from the end of the piston contacted by a Luer tip in order to permit the flow of fluid from the Luer tip through the valve.
In addition, the Raines valve is subject to difficulties in manufacture because of flash since the various outlet ports are angularly, i.e., perpendicularly, oriented in relation to their inlets.
Other arrangements are disclosed in Newgard, U.S. Pat. No. 5,064,416; Sivert, U.S. Pat. No. 4,915,687 and Jackson, U.S. Pat. No. 4,429,856.These arrangements are complex, are difficult to manufacture and have numerous disadvantages.
Another objection to existing arrangements is that their activators are not interchangeable. Thus, injection sites that require needle injection cannot be used without needles; conversely injection sites that are externally actuated by inserting a member that opens a diaphragm cannot be used with needles. In addition, the non-needle injection sites present problems of sterility. In order to have external access to the control diaphragm, it is necessary to have an open channel that can become contaminated. Even when a temporary seal is provided for the open channel, removal of the seal prior to the injection allows inadvertent contamination. This is by contrast with an injection site having a needle-puncturable surface. The latter can be wiped clean with a sterilizing agent before injection is to take place.
Accordingly, it is an object of the invention to achieve needleless injection, infusion and aspiration without the need for spring-loaded members, such as pistons or spools where the counterforce exerted by the spring increases as the piston is displaced. A related object of the invention is to overcome the disadvantages characterizing the needleless injection valves of Rogers, U.S. Pat. No. 5,006,114 and Raines, U.S. Pat. No. 5,147,333.
A further object of the invention is to overcome the need for angular orientation of an outlet in relation to an inlet in order to avoid manufacturing difficulties such as the creation of flash which can clog or reduce the volume of fluid flow from an inlet to an outlet.
Yet another object of the invention is to permit the non-use of projections on a closure for an inlet, whereby a Luer fitting can open an inlet channel without the need for engaging one or more projections on a closure.
A further object of the invention is to enhance the control that can be achieved over fluid flow. A related object is to enhance flow control where fluid infusion or combination is to take place.
An important object of the invention is to eliminate the need for needle usage at injection sites, while permitting needle usage if that is desired. A related object is to maintain sterility at injection sites that are operated without needles, while simultaneously permitting such sites to be used with needles if necessary.
An additional object of the invention is to improve the performance of valves for infusion, injection, aspiration and control of fluid flow.